What happened to my account

So I was using Twitter today when I checked one of the notifications and saw that my reply wasn't showing.

I went to my profile and saw it was diferent; the profile picture and banners were filled ( something I don't use). Many of my posts and reposts are missing, i following what are possibly bots, which I've never done and most absurd of all, my @ has changed

Original@ = SkyDrifter25

replaced with = lunnac403429

I don't know what I did or how it happened, but I want to know how to fix it, especially since I'm worried it can affect my other accounts, even important ones